For the last several decades there have been repeated warnings concerning energy shortages. The general pattern has been for energy prices to spike sharply resulting in a significant economic downturn which temporarily takes the pressures off of energy supplies. At the same time half-hearted energy conservation measures are established. In the past this resulted in a temporary drop in energy prices so that rampant energy consumption soon resumed and energy conservation and long-term energy planning were completely forgotten. At this time the rapid development of China and India are placing increasing pressure on energy supplies. This demand seems likely to cushion the typical cyclic drop in prices. Recently the price of oil spiked to $150.00 per barrel or more, and it seems as if prices may eventually return to those levels if energy conservation is not improved and new energy sources are not found.
Furthermore, energy supplies are finite. Best estimates are that oils supplies will be mostly depleted within forty or so years. Even with the discovery of new oil fields and improved recovery from existing fields, this estimate is highly unlikely to be increased even two-fold to eighty years. Thus, baring drastic improvements in efficiency or tremendous conservation efforts, some individuals who are now alive will almost certainly see the end of a petroleum powered world just as our ancestors not that many generation back saw the end of a horse powered technology. Some have pinned their hopes on nuclear power. Unfortunately, the supply of nuclear fuel is also limited particularly considering the inefficient nuclear reactors now in use. Furthermore, the nuclear waste problem is so critical that our civilization could probably not safely depend on nuclear energy even if the fuel supply were unlimited.
The picture for other popular fossil fuels is not much brighter than that for oil. It is estimated that current natural gas supplies will be exhausted in about sixty years. Even if the estimated time is doubled, it would appear that wide spread dependence on natural gas will end in no more than one hundred and twenty years. Coal is perhaps the most abundant fossil fuel; there is thought to be at least a 200 year supply. That means that unless alternative energy technologies are soon developed our civilization will become entirely dependant on coal within the next fifty to one hundred years. Yet coal is the fossil fuel that was developed earliest and was largely supplanted by oil and natural gas because coal combustion is dirty and leaves large volumes of ash. Not to mention the terrible environmental costs of coal mining.
However, it is probably not a shortage of coal that will necessitate an abandonment of coal use. Rather it will be the environmental consequences of continued release of fossil carbon dioxide into the atmosphere. This problem, often called global warming, results from combustion of any fossil fuel. It is just that oil will probably be exhausted before the full brunt of the problem is felt. Global warming is probably not a good term because while overall global temperatures are increasing due to excess atmospheric carbon dioxide, the real problem is not warming per se but rather is drastic climate change. The Earth's climate is always changing—at some times more rapidly that at other times. For example, during the relatively recent past drastic climate change that took place at the end of the ice age; this climate change although rapid by geological standards was sufficiently slow that living organisms could either adjust to the new climate or relocate to an area with a more amenable climate. Thus as the glaciers retreated and temperatures warmed “arctic” species adapted to cold temperatures moved north or into higher elevations. There is every indication that the climate changes resulting from burning of fossil fuels will be too rapid to allow living organisms to relocate. The result will be extreme loss of species and overall biological diversity with a species extinction rate much higher than the already high extinction rate caused by the spread of our civilization.
Until some entirely new energy source such as fusion is perfected, the best answer to the energy conundrum would appear to be greatly increased conservation coupled with exclusive use of renewable energy sources. Most energy on our planet comes ultimately from the sun. Therefore, solar energy in the form of photovoltaic electricity and solar heating are ideal. However, direct solar energy cannot satisfy all of our needs. Hydroelectric power and wind generated power are two other forms of renewable solar-based energy. None of these power sources result in changes in atmospheric carbon dioxide. Biomass energy (i.e., wood and other plant materials) may be the ideal complement to solar energy. This may seem surprising because biomass energy is normally obtained through combustion of the biomass, and such combustion releases carbon dioxide into the atmosphere. However, biomass is renewable. If plantations of green plants are grown to produce biomass, the released carbon dioxide will quickly be sequestered in new plant material. Thus, the carbon dioxide is used over and over, and the total level of atmospheric carbon dioxide does not continue to increase, as with the burning of fossil fuels. The real problem is how to integrate biomass energy into our economy. There is presently a marked shortage of wood burning stream trains and wood burning automobiles. Nor is direct combustion of biomass in power plants particularly viable because our electrical generation systems are adapted to use liquid oil or natural gas or even pulverized coal.
There has been considerable effort to produce liquid fuel (primarily ethanol) from biomass. This involves fermentation of sugars derived directly from plant products like corn or indirectly from the digestion of cellulosic biomass into fermentable sugars. The technology for fermenting directly derived sugars is well established. Presently, the United States is increasingly moving towards a fuel system based on ethanol derived from corn. While this approach may be politically favored by corn raising areas, it contains a potentially fatal flaw. Diversion of corn from food uses may result in a dramatic increase in food prices. Even more of a problem is the considerable requirement of nitrogen fertilizer for efficient cultivation of corn. The primary source of nitrogen fertilizer is an energy intensive industrial process that consumes almost as much energy as is captured in corn derived ethanol. This is particularly true because only a fraction of the energy in the corn plant is captured by converting corn grain into ethanol. A great deal of energy remains in the cellulosic biomass of the plant and is not reclaimed as ethanol.
Probably, the greatest potential source of renewable energy is in cellulosic biomass. The conversion of cellulose into fermentable sugar is difficult and at the present not terribly efficient. Typically enzymes or acids are used to hydrolyze the cellulosic biomass into fermentable sugars. Adequate mechanical pretreatment of the biomass is essential. In some processes the biomass is chemically pretreated and then “exploded” by rapid changes in temperature and pressure. Such processes may create large amounts of hazardous chemical waste. Other processes cook wood chips in acid in devices rather like those used to produce wood pulp for paper manufacturing. To date none of these approaches has proven to be highly successful. The present inventor has earlier tried to solve the problems of the present technology by reducing biomass into sufficiently small particles. The inventor found that such particles (called cellulosic micropowder) can be readily hydrolyzed into sugars and other organic monomers either by means of enzymes or by means of chemical hydrolysis. Probably because of the very small size of the particle, hydrolytic enzymes are far more effective than they are on cellulosic biomass prepared in other ways. The main drawback of this approach appears to be the complexity of the devices used to make the micropowder and the energy consumed by them. Therefore, the inventor has attempted to develop an even more efficient method to convert cellulosic biomass into fermentable sugars.